Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment

Lucas N. Joppa, Stuart H M Butchart, Michael Hoffmann, Steve P. Bachman, H. Resit Akçakaya, Justin F. Moat, Monika Böhm, Robert A. Holland, Adrian Newton, Beth Polidoro, Adrian Hughes

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

In International Union for Conservation of Nature (IUCN) Red List assessments, extent of occurrence (EOO) is a key measure of extinction risk. However, the way assessors estimate EOO from maps of species' distributions is inconsistent among assessments of different species and among major taxonomic groups. Assessors often estimate EOO from the area of mapped distribution, but these maps often exclude areas that are not habitat in idiosyncratic ways and are not created at the same spatial resolutions. We assessed the impact on extinction risk categories of applying different methods (minimum convex polygon, alpha hull) for estimating EOO for 21,763 species of mammals, birds, and amphibians. Overall, the percentage of threatened species requiring down listing to a lower category of threat (taking into account other Red List criteria under which they qualified) spanned 11-13% for all species combined (14-15% for mammals, 7-8% for birds, and 12-15% for amphibians). These down listings resulted from larger estimates of EOO and depended on the EOO calculation method. Using birds as an example, we found that 14% of threatened and near threatened species could require down listing based on the minimum convex polygon (MCP) approach, an approach that is now recommended by IUCN. Other metrics (such as alpha hull) had marginally smaller impacts. Our results suggest that uniformly applying the MCP approach may lead to a one-time down listing of hundreds of species but ultimately ensure consistency across assessments and realign the calculation of EOO with the theoretical basis on which the metric was founded.

Original languageEnglish (US)
Pages (from-to)362-370
Number of pages9
JournalConservation Biology
Volume30
Issue number2
DOIs
StatePublished - Apr 1 2016

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extinction risk
risk assessment
extinction
natural resources conservation
threatened species
hulls
amphibians
birds
mammals
polygon
Red List
hull
bird
amphibian
biogeography
mammal
habitats
methodology
spatial resolution
habitat

Keywords

  • Distribution maps
  • IUCN Red List
  • Threatened

ASJC Scopus subject areas

  • Ecology
  • Nature and Landscape Conservation
  • Ecology, Evolution, Behavior and Systematics

Cite this

Joppa, L. N., Butchart, S. H. M., Hoffmann, M., Bachman, S. P., Akçakaya, H. R., Moat, J. F., ... Hughes, A. (2016). Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology, 30(2), 362-370. https://doi.org/10.1111/cobi.12591

Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. / Joppa, Lucas N.; Butchart, Stuart H M; Hoffmann, Michael; Bachman, Steve P.; Akçakaya, H. Resit; Moat, Justin F.; Böhm, Monika; Holland, Robert A.; Newton, Adrian; Polidoro, Beth; Hughes, Adrian.

In: Conservation Biology, Vol. 30, No. 2, 01.04.2016, p. 362-370.

Research output: Contribution to journalArticle

Joppa, LN, Butchart, SHM, Hoffmann, M, Bachman, SP, Akçakaya, HR, Moat, JF, Böhm, M, Holland, RA, Newton, A, Polidoro, B & Hughes, A 2016, 'Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment', Conservation Biology, vol. 30, no. 2, pp. 362-370. https://doi.org/10.1111/cobi.12591
Joppa LN, Butchart SHM, Hoffmann M, Bachman SP, Akçakaya HR, Moat JF et al. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology. 2016 Apr 1;30(2):362-370. https://doi.org/10.1111/cobi.12591
Joppa, Lucas N. ; Butchart, Stuart H M ; Hoffmann, Michael ; Bachman, Steve P. ; Akçakaya, H. Resit ; Moat, Justin F. ; Böhm, Monika ; Holland, Robert A. ; Newton, Adrian ; Polidoro, Beth ; Hughes, Adrian. / Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. In: Conservation Biology. 2016 ; Vol. 30, No. 2. pp. 362-370.
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